1. Field Of The Invention
The present invention relates generally to a bumper mount structure for automotive vehicles.
2. Description Of Related Art
Japanese Patent Application Laid-open No. 4-31152 teaches an automotive bumper mount structure in which bumper brackets are mounted on the front of front side members through bumper stay reinforcements. When the vehicle is involved in a front-end collision, the front side members and the bumper brackets are collapsed in the longitudinal direction thereof to absorb the energy of impact.
Japanese Patent First Publication No. 4-287742 teaches another type of bumper mount structure in which a bumper stay is installed on each front side member using a bolt and a nut so that it may be turned upon occurrence of a vehicle collision to impinge on the front side member, thereby causing the moment produced from the bolt and the nut and the moment produced by the interference of the bumper stay with the front side member to be balanced to absorb the energy of impact effectively.
Usually, when the vehicle is involved in an offset collision, it will cause a bumper reinforcement to be bent, so that a side member and a bumper bracket on the side of the collision are collapsed longitudinally. The other side member is attracted inwardly to produce torsional moment which will cause a bumper bracket on the opposite side of the collision to be deformed.
At the instant of the offset collision, the side member on the opposite side of the collision will produce some reactive force, but the bending of the bumper reinforcement reduces the reactive force. It is, thus, important to avoid the bending of the bumper reinforcement by, for example, increasing the thickness thereof, however, resulting in a undesirable increase in weight.
In the latter structure in which the bumper stay is mounted rotatably by the bolt, the load of the bolt concentrates at the upper and lower ends of the bumper stay, thus requiring reinforcement of the ends of the bumper stay, which will lead to an increase in weight thereof.
It is an object of the present invention to provide a simple and light-weight bumper mount structure designed to minimize undesirable bending of a bumper bracket upon occurrence of an offset collision to transmit an axial collapsing pressure to a side member with high efficiency.
According to one aspect of the invention, there is provided a vehicle body which comprises: (a) side members disposed on sides of the vehicle body, the side member extending in a longitudinal direction of the vehicle body; (b) a bumper reinforcement; and (c) bumper brackets joining the bumper reinforcement to ends of the side members, respectively, each of the bumper bracket being made of one of an extruded material and a cast material and having a boss, the boss having formed therein a vertical hole extending vertically of the vehicle body and establishing connection of the bumper reinforcement and a corresponding one of the side members through a fastening member which is fitted within the vertical hole of the boss so as to allow the bumper bracket to rotate around the fastening member.